The present invention relates to a display apparatus on a vehicle for visibly informing a passenger of the presence/absence of, e.g., obstacles or the like present around the vehicle and, for example, to a display apparatus provided on an automobile as a representative vehicle.
Conventionally, an apparatus for sensing an image of a space around a vehicle using an infrared image sensing device, and displaying the sensed image on a unit in front of the driver""s seat is proposed in, e.g., Japanese Patent Laid-Open No. S60-231193, Japanese Patent Application No. H6-247184, Japanese Patent Laid-Open Nos. H9-39658, H10-230805, and the like. According to such apparatuses, the driver can easily recognize the presence of obstacles (heat sources such as people, animals, or the like that may interfere with safe maneuvering of the vehicle) even in a situation (e.g., night, heavy fog, or the like) around the vehicle that the driver can hardly recognize such obstacles even when he or she turns on head lamps, and such apparatuses can effectively support the maneuvering.
However, in such conventional apparatuses, it is a common practice to locate a display for displaying an image at a position in front of the driver seat so that it is easy for the driver to see. Since the image is always displayed on this display in an identical display pattern irrespective of the surrounding environment around the vehicle, it is expected to become a heavy load on the driver""s sight.
It is, therefore, an object of the present invention to provide a display apparatus on a vehicle, which can satisfactorily display the situation around the vehicle, and can appropriately change its display pattern in correspondence with the surrounding environment.
In order to achieve the above object, a display apparatus on a vehicle according to the present invention is characterized by the following arrangement.
That is, the invention according to claim 1 is a display apparatus on a vehicle, which comprises image sensing means (2, 103) for sensing an image ahead of the vehicle using infrared rays, and display means (3A, 3B, 108) for displaying an infrared image sensed by the image sensing means at a position in front of a driver""s seat in a passenger room of the vehicle, characterized by comprising surrounding environment detection means (2, 4, 6, 8, 18, 102, 104-107) for detecting a surrounding environment of the vehicle, and display control means for controlling the display means (1, 101) on the basis of a detection result of the surrounding environment detection means, and in that the display control means checks whether or not the surrounding environment detected by the surrounding environment detection means requires display of the infrared image on the display means, and when it is determined that the surrounding environment does not require display of any infrared image, display of the infrared image on the display means is suppressed compared to a case wherein it is determined that the surrounding environment requires display of the infrared image.
According to the invention of claim 1, since the situation around the vehicle can be satisfactorily displayed, and the display pattern can be appropriately changed in accordance with the surrounding environment, visual and mental loads on the drive operation of the driver can be reduced.
In the display apparatus on a vehicle according to claim 1, when it is determined as the surrounding environment that the vehicle is traveling in a surrounding environment in which a heat source that may interfere with safe maneuvering is highly likely to be present ahead of the vehicle, the display control means preferably suppresses display of the infrared image on the display means compared to a case wherein it is determined that the vehicle is traveling in a surrounding environment in which the heat source is unlikely to be present.
In the display apparatus on a vehicle according to claim 1, when it is determined as the surrounding environment that the vehicle is traveling on a motorway in an urban area, the display control means preferably suppresses display of the infrared image on the display means compared to a case wherein it is determined that the vehicle is traveling on a normal road.
Since a road such as a motorway or the like is designed to allow efficient travel of automobiles, obstacles are unlikely to be present ahead of the self vehicle, and the display pattern can be adequately restricted in such surrounding environment.
In this case, as an example of the method of suppressing display of an infrared image, when it is detected as the surrounding environment that another stalled vehicle is present ahead of the vehicle, the display control means preferably inhibits suppression of display of the infrared image on the display means.
Note that as a preferred embodiment for checking whether or not another vehicle is present, the surrounding environment detection means preferably includes obstacle detection means (4, 102) for detecting distance to an obstacle present ahead of the vehicle, and the display control means determines the presence/absence of the other stalled vehicle on the basis of a detection result of the obstacle detection means. Or the surrounding environment detection means may include road-vehicle communication means (18) for receiving information that pertains to a traveling state of another vehicle present ahead of the vehicle from a transmitter provided in a communication infrastructure on a road side, and the display control means may determine the presence/absence of the other stalled vehicle on the basis of a reception result of the road-vehicle communication means.
In the display apparatus on a vehicle according to claim 1, the display control means inhibits display of the infrared image as suppression of display of the infrared image on the display means.
As an example of the method of suppressing display of an infrared image, the apparatus preferably comprises as the display means a first display (3A) which is laid out in advance at a position within a field-of-view range of a driver who looks forward, and a second display (3B) which is laid out in advance at a position near an outer edge of the field-of-view range compared to the layout position of the first display, and the display control means stops display of the infrared image on the first display as suppression of display of the infrared image on the display means.
In this case, in a preferred embodiment, when it is determined that the surrounding environment detected by the surrounding environment detection means does not require display of any infrared image on the display means, the display control means preferably displays the infrared image only on the second display, and when it is determined that the surrounding environment requires display of the infrared image, the display control means preferably displays the infrared image only on the first display. Or when it is determined that the surrounding environment detected by the surrounding environment detection means does not require display of any infrared image on the display means, the display control means may display the infrared image only on the second display, and when it is determined that the surrounding environment requires display of the infrared image, the display control means may display the infrared image on the first and second displays.
In the display apparatus on a vehicle according to claim 1, the display control means may suppress display of the infrared image on the display means by decreasing a display luminance of the display means or by decreasing size of a display area of the display means.
In the display apparatus on a vehicle according to claim 1, when it is determined as the surrounding environment that the vehicle is traveling trailing the path of another vehicle which is traveling ahead of the vehicle so as to maintain a distance from the other vehicle at a predetermined value, the display control means suppresses display of the infrared image on the display means compared to a case wherein it is determined that the vehicle is not traveling trailing the path of the other vehicle.
In this case, as a preferred embodiment of determining whether or not the vehicle is trailing another vehicle, the surrounding environment detection means preferably includes road-vehicle communication means (18) for receiving information that pertains to a traveling state of another vehicle present ahead of the vehicle from a transmitter provided in a communication infrastructure on a road side, and the display control means determines on the basis of a reception result of the road-vehicle communication means whether or not the vehicle is trailing along behind the other vehicle.
As a preferred embodiment of suppressing display of an infrared image, when it is determined that the vehicle is traveling trailing the path of the other vehicle and the predetermined value is set to be smaller than a headlight irradiation range of the vehicle, the display control means preferably suppresses display of the infrared image on the display means compared to a case wherein the predetermined value is set to be larger than the headlight irradiation range. Or when the predetermined value is smaller than a threshold value set in accordance with a traveling velocity of the vehicle, the display control means may suppress display of the infrared image on the display means compared to a case wherein the predetermined distance is larger than the threshold value (in this case, the threshold value is preferably set to increase in accordance with increasing traveling velocity of the vehicle).
In the display apparatus on a vehicle according to claim 1, when it is detected as the surrounding environment that a pedestrian crossing is present ahead of the vehicle, the display control means suppresses display of the infrared image on the display means compared to a case wherein no pedestrian crossing is detected.
With this invention, when a pedestrian crossing is detected, since restrictions such as a reduction of the display intensity, reduced-scale display, and the like are canceled, the driver""s sight can be adequately supported, and the driver can easily recognize a pedestrian who may be crossing the detected pedestrian crossing.
As a preferred embodiment of suppressing display of an infrared image, when a distance between the vehicle and the pedestrian crossing is larger than a predetermined value, the display control means preferably suppresses display of the infrared image on the display means compared to a case wherein the distance is smaller than the predetermined value (in this case, the predetermined value is preferably set to increase in accordance with increasing traveling velocity of the vehicle). Or the display control means may include a manual operation switch (113) which allows a passenger to turn on/off a control function of suppressing display of the infrared image on the display means.
In the display apparatus on a vehicle according to claim 1, when the presence of a person ahead of the vehicle is not detected as the surrounding environment, the display control means suppresses display of the infrared image on the display means compared to a case wherein the presence of a person is detected (note that the display control means preferably includes a manual operation switch (113) which allows a passenger to turn on/off a control function of suppressing display of the infrared image on the display means).
In this case, as a preferred embodiment of detecting whether or not a person is present, the surrounding environment detection means (103) preferably determines the presence of a person ahead of the vehicle when it is detected that the infrared image sensed by the image sensing means includes a heat source within a predetermined temperature range corresponding to radiation heat of a person.
Also, as a preferred embodiment of determining whether or not a heat source within a predetermined temperature range corresponding to radiation heat of a person is included, the surrounding environment detection means preferably includes at least one of temperature detection means (107) for detecting atmospheric temperature of the vehicle, and date and time detection means (105) for detecting a current date and time, and the display control means adjusts the predetermined temperature range on the basis of the atmospheric temperature detected by the temperature detection means and/or the current date and time detected by the date and time detection means as the surrounding environment.
In the display apparatus on a vehicle according to claim 1, when the presence of an on-coming vehicle is not detected as the surrounding environment, the display control means suppresses display of the infrared image on the display means compared to a case wherein the presence of an on-coming vehicle is detected (note that the display control means preferably includes a manual operation switch (113) which allows a passenger to turn on/off a control function of suppressing display of the infrared image on the display means).
In this case, as a preferred embodiment of determining whether or not an on-coming vehicle is present, the surrounding environment detection means (104) preferably detects the presence/absence of the on-coming vehicle by checking whether or not light irradiating the vehicle comes from head lamps of another vehicle.
With this invention, when light coming from the head lamps of an on-coming vehicle is detected (in such case, the driver can hardly recognize the situation of the road ahead), since restrictions such as a reduction of the display intensity, reduced-scale display, and the like are canceled, the driver""s sight can be adequately supported.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.